This report reviews morphologic aspects of pericardial heart disease. A morphologic classification for this condition is presented. An ideal classification of pericardial heart disease obviously would take into account clinical, etiologic, and morphologic features of this condition, but a single classification combining these three components is lacking. Pericardial heart disease is relatively uncommon clinically and when present at necropsy, it usually has not been recognized during life. The term "pericarditis" is inaccurate because most pericardial diseases are noninflammatory in nature. Morphologically, chronic pericardial heart disease may present clinically as an acute illness. Even when clinical symptoms are present, however, few patients develop evidence of cardiac dysfunction (constriction). When pericardial "constriction" occurs, it is the result of increased pericardial fluid or increased pericardial tissue or both. Increased fluid is treated by drainage; increased tissue, by excision. In most patients with chronic constrictive "pericarditis," the etiology is not apparent, even after histologic examination of pericardia.